Solve for $x$ and $y$ using substitution. ${5x+2y = -7}$ ${x = 2y+1}$
Explanation: Since $x$ has already been solved for, substitute $2y+1$ for $x$ in the first equation. ${5}{(2y+1)}{+ 2y = -7}$ Simplify and solve for $y$ $10y+5 + 2y = -7$ $12y+5 = -7$ $12y+5{-5} = -7{-5}$ $12y = -12$ $\dfrac{12y}{{12}} = \dfrac{-12}{{12}}$ ${y = -1}$ Now that you know ${y = -1}$ , plug it back into $\thinspace {x = 2y+1}\thinspace$ to find $x$ ${x = 2}{(-1)}{ + 1}$ $x = -2 + 1$ ${x = -1}$ You can also plug ${y = -1}$ into $\thinspace {5x+2y = -7}\thinspace$ and get the same answer for $x$ : ${5x + 2}{(-1)}{= -7}$ ${x = -1}$